Kubernetes vs Docker Swarm: A comparison of cloud container tools

Kubernetes and Docker Swarm are two of the most powerful IT cloud container management weapons.

Containers are rising like a hot air balloon in the cloud market. These days, the CIO can hardly move for suggestions of one-shot-wonder tools to lighten the burden of IT infrastructure management. But when it comes to the battle of Kubernetes vs Docker, which programme comes out on top?

Touted as silver bullet simplifiers of software update administration, both tools are great for transporting applications from one system to another without risking compatibility problems, missing files or unexpected errors. In the first instance, using a container to transport applications is much faster and better value than using a virtual machine, so either product is a good place to start for boosting cloud architecture efficiency.

Either smart platform will help the IT manager to create, deploy and manage software containers for a range of business uses, although Kubernetes works at a slightly different level than Docker Swarm. But what exactly can these programmes do?

Put simply, Kubernetes is a tool allowing the IT manager to run multiple containers in parallel. Think of it as a container dashboard; if your containers are musicians, then Kubernetes is the conductor.

Docker is a container platform with a panoply of management options for any type of cloud set-up, providing fine control over applications independent of infrastructure. The tool we are interested in is Docker Swarm, a flexible container storage platform which some consider more straightforward to use than Kubernetes.

Let’s get into the differences, overlap and how to choose between them.

Kubernetes: How it works (and how it doesn’t)

Created by Google in 2014, Kubernetes is an IT management tool designed to simplify the scalability of workloads using containers.

Kubernetes can be used to amplify cloud containerisation strategy as it is designed to automate deploying, scaling and operating application containers. A big perk of Kubernetes is how readily it integrates with any cloud portfolio, be it public, private, hybrid or multi-cloud.

The programme runs on Ubuntu, RHEL, CoreOS, on-prem, Google Kubernetes Engine, and anywhere else. It does not restrict compatibility to certain programming languages, nor does it distinguish between apps and services, leading many to praise its flexibility.

Kubernetes is modular, which means it is designed to aid the agile creation and deployment of enterprise applications. Kubernetes works on operating-system-level virtualization rather than hardware virtualization, meaning it runs faster than the traditional VM approach.

Its most useful function is the distribution of computation workload between the containers as it enables containers to run across numerous computers at the same time. A key business benefit of this flexibility is the possibility of scaling operations up or down by switching individual containers on or off across the network. The tool also makes light work of service-discovery, cluster administration, loadbalancing and dealing with network policies. It can also aid in delivery of rolling updates, debugging applications and providing authentication and authorisation.

A common criticism of Kubernetes, however, is that it can be overly complex. For instance, debugging issues in a Kubernetes cluster requires a fairly deep understanding of container networking, including namespaces, the DNS server and network interfaces. Programmers have also reported difficulty in deploying executables with zero downtime, as this is not the default.

Kubernetes is not a service which provides data processing frameworks and will not build a container for the application (unlike Docker, Jenkins and others), so the tool is not a solution to continuous integration (CI).

Docker Swarm: Upsides and downfalls

Docker Swarm can help IT coordinators run multiple containers in tandem, making it an ace tool for container orchestration. Docker Swarm enables managers to deploy several containers at once (known as “Swarm”) and then control this as if it were a set group.

The tool is a native clustering system which comes with a simple scheduling backend and as development gets underway, will develop an API to enable pluggable backends for large scale production deployments. As Docker puts it: “A swarm is a group of machines that are running Docker and joined into a cluster. After that has happened, you continue to run the Docker commands you’re used to, but now they are executed on a cluster by a swarm manager.” This is brilliant, as the Docker engine is deployed across multiple nodes, boosting the IT manager’s ability to orchestrate services.

Docker as a company is one year older than Kubernetes, meaning Docker Swarm has the backing of a much broader containerisation management ecosystem to support it. It is a much more established and industry-standard tool compared to its younger cousin.

Aimed at a more general-use audience than Kubernetes, Docker’s Command Line Interface (CLI) means its installation and set-up is typically more straightforward for the uninitiated to grasp.

When it comes to monitoring node clusters, Docker can fall down compared with Kubernetes, as it has no integrated monitoring or logging workspace. Computer programmers will need to use third party tools for this purpose, which is simple enough to do but is an extra step absent in Kubernetes.

Kubernetes vs Docker: Combined uses and price comparison

Kubernetes boasts of corporate partnerships with eBay, SAP, Philips, the Home Office, Goldman Sachs, Monzo, Pokemon Go and more. IBM has also written about its usefulness for the enterprise. Like Docker Swarm, Kubernetes is designed to limit hardware use to match business resource requirement, meaning either tool presents money-saving opportunities.

By contrast, Docker Enterprise claims it is the world’s most-used software container platform. Both tools run on Windows or Linux systems; perhaps the question is not ‘which is better?’ but ‘which is right for my business needs right now?’

Docker is open source: the two favourite words of the cash-strapped IT budget manager. Yet this only applies to the Community edition, offering a basic version range of tools such as automated builds as a service and one free private repo storage as a service. Docker Swarm can be downloaded without purchasing the full Enterprise Edition, though Community does not offer the full scalability of the integrated lifecycle management or certified infrastructure of its paid counterpart.

By contrast, Kubernetes is fully open source. Many developers use the software successfully by trial-and-error experimentation of how the tool can work for business-specific needs. Paid support and related services are available through organisations such as CoreOS, acquired by Red Hat and Microsoft-owned Deis. However, free assistance on either Kubernetes or Docker is generally available on community sharing website, Stack Overflow.

Docker Enterprise Edition (EE), the paid version of Docker’s container management toolkit, is marketed as a Containers-as-a-Service platform which offers integrated management of all app resources on one dashboard. Authorised resellers are: Canonical, Microsoft, IBM and HPE and pricing per node ranges from £652 to £3,043, depending on the level of business support desired. Initial orders must number at least five nodes and prices do not include VAT. Two days of staff training for up to 20 individuals is available from £15,600 through Quru.

While Kubernetes boasts of its wide-branching ecosystem of components for application deployment and management, Docker EE advertises its built-in security framework as a selling point for its enterprise product.

In fact, Kubernetes can now use the Docker engine to assist its management capabilities, leading many IT businesspeople to combine both tools for DevOps strategy and more. Following rivals such as Mesosphere, Docker has now opened itself up to allowing use of Kubernetes as a container orchestration system within its platform. This increased compatibility indicates Kubernetes is not going to disappear any time soon and the companies are even collaborating for the good of containerisation standardisation.

Budget and business use are therefore major factors in deciding which tool to use and when.

The verdict

Kubernetes vs Docker need not be an either/or choice, as each is a slightly different tool and the latter has even deployed a compatibility update for the former. While Kubernetes can appear more flexible due to its modular approach and wide range of cloud service interconnections, it is worth remembering that it is made by Google developers and will therefore always follow the web service’s worldview.

Given the breadth of this worldview (we’re talking about the inventor of Google Maps, here), this may spark no concerns whatsoever. By comparison, the community-created modifications on Docker available on GitHub and elsewhere could make the platform more usable in the eyes of some. More than anything, a company must ask itself which software applications or services it is trying to containerise and why.

Products should never be chosen before business use has been nailed down – tools are only ever a means to an end, not an answer in themselves.